WO1997047729A1

WO1997047729A1 - Sensing unit for monitoring the contents of a fluid-containing container

Info

Publication number: WO1997047729A1
Application number: PCT/GB1997/001531
Authority: WO
Inventors: Anthony Hugh Carr
Original assignee: Oxoid Limited
Priority date: 1996-06-11
Filing date: 1997-06-09
Publication date: 1997-12-18

Abstract

A sensing unit for monitoring the contents of a fluid containing container, such as a liquid culture bottle, wherein the interior of the container, which is liable to pressure variations, is placed in sealed communication with the interior of a housing of the sensing unit, wherein may be located a sensor responsive to a parameter of the container contents, and the sensing unit housing also incorporates a pressure relief valve. An exemplary pressure relief valve is the click on/click off type with respect to manual operation, but preferably a solenoid drive means is also provided for opening the valve automatically.

Description

Title Sensing Unit for Monitoring the Contents of a Fluid-containing Container

Field of the Invention

This invention relates to a sensing unit for monitoring the contents of a fluid-containing container, more especially in the case where the container is sealed and is liable to internal pressure variations.

Background to the Invention

From prior published Patent Specification No. WO 93/03178 is known a method of monitoring the growth of microorganisms in a liquid culture in which pressure variations in the headspace of a bottle containing the liquid culture are sensed. The bottle is provided with a sealed closure incorporating a flexible septum and deflections of the septum are detected by a laser. The detected deflections are fed to a remote signal processing unit.

Known from European Patent Specification No. 0592728 Al is a sensing unit for the same purpose, which fits directly to the sealed closure of the container and includes a hollow needle for puncturing the septum to place the bottle headspace in communication with a pressure transducer in the sensing unit, from which signals may be sent to remote electronics.

Copending European Patent Application No.96304359.1 proposes a self-contained sensing unit for fitting to the sealed top of the bottle and which includes a pressure transducer, an algorithm containing signal processor, and display means. In accordance with copending European Patent Application No. 96304356.7 this sensing unit sealing fits to a modified bottle closure which incorporates a hollow needle caused to puncture the septum as the sensing unit is fitted to the closure, placing the bottle interior in communication with the pressure transducer in the sensing unit.

In the prior art, it is suggested in Specification No. WO 93/03178 that the laser used to detect deflections of the septum may carry a venting needle if a bottle is sensed as having developed an excess internal pressure.

The Invention

According to the present invention, in its broadest aspect, there is provided a sensing unit for monitoring the contents of a sealed fluid-containing container, comprising a housing having means enabling its connection to the container, the housing including a passage means through which the housing interior in use communicates with the container interior, whereby the container interior liable to pressure variations is placed in sealed communication with the housing to enable the container contents to be monitored, wherein the housing of the sensing unit incorporates a pressure relief valve which includes a valve member located in a branch of said passage means communicating with atmosphere.

It will be understood that, in the context of the invention, "pressure relief" means relief of either overpressure or underpressure within the container.

The pressure relief valve is preferably both manually operable and operable by a powered drive means. In the latter case, a measurement device such as a pressure transducer in the housing may be responsive to pressure variations within the container and in the event of a predetermined upper or lower pressure limit being exceeded produces a drive signal for the drive means. Conveniently, the drive means is a solenoid.

In a preferred arrangement, the valve member is located in an enlargement in the said branch of the passage means into which opens a narrower passageway, and the valve member acts to open and close the mouth of the passageway. Such valve member may conveniently be a rubber element compressed against the mouth of the passageway in the closed condition and displaced away from the passage- way in the open condition.

Whether or not the valve member is arranged in the last described manner, preferably the valve member incorporated in the pressure relief valve is operable by an operating means having two spaced latched positions, one in which the pressure relief valve is closed and one in which it is open. The operating means may comprise a spring loaded, axially displaceable stalk interposed between the valve member and a ratchet element releasably engageable with either one of two latches spaced apart in the axial direction.

For manual operation, the ratchet element is preferably disengageable from a closed condition latch and axially displaceable under spring action to engage an open condition latch by means of a finger operable member displaceable in the axial direction on said ratchet member, while for automatic operation the ratchet element is disengageable from a closed condition latch and axially displaceable under spring action to engage an open condition latch by means of a solenoid driven, spring loaded member acting laterally to release the ratchet element by withdrawal of said closed condition latch. In either case, in order to restore the closed condition of the valve, the finger operable member may also be axially displaceable to drive the ratchet element against the spring action out of engagement with the open condition latch and into engagement with the closed condition latch.

In the preferred arrangement, the ratchet element has two pawls, one on each side of the element, and a guide along which the stalk and ratchet element are displaceable has the two latches on opposite sides of the path of movement of the ratchet element, said ratchet element being tiltable from side to side, accompanied by flexure of the stalk, to enable the pawls to engage the respective latches.

Especially when applied to monitor pressure variations in the headspace of a partially filled culture bottle, the housing is preferably adapted to fit sealingly to a closure device on the top of the container, and thereby automatically place the container interior in communication with the pressure transducer when the pressure valve is closed. In this way it is ensured that the bottle contents are not contaminated by fitting of the sensing unit, whether by temporary exposure to atmosphere or otherwise.

Description of Embodiment

The invention is further described, by way of illustration, with reference to the accompanying drawings, in which:- Figure 1 shows the closed top of a culture bottle with the sensing unit ready for fitting thereto;

Figure 2 is a diagrammatic view showing the pressure relief valve and associated passage means within the housing of the sensing unit;

Figures 3A to 3E show a sequence of stages involved in manual operation of the pressure relief valve; and

Figures 4A and 4B show two stages involved in automatic operation of the pressure relief valve.

Detailed Description of the Drawings

The drawings show a culture bottle 10 fitted with a rubber septum 12 held in place by a crimped aluminium seal 14. The septum carries an integral chimney 18 housing a puncturing device 20 which includes a needle 30. The sensing unit, which incorporates the pressure relief valve (not shown in Figure 1), comprises a housing 24 also accommodating a pressure transducer, an algorithm containing signal processor, and a display device 26. The underside of the housing 24 has a boss 28 which sealingly fits into the top of the chimney 18, thereby to depress the puncturing device and cause the needle 30 to puncture the septum 12, thereby placing the headspace 16 in the bottle in communication with the pressure transducer.

Figure 2 shows the interior of the housing 24 of the sensing unit, omitting all parts except the pressure transducer, the pressure relief valve and the associated passage means which communicate with the interior of the culture bottle via the septum puncturing device.

In Figure 2, the body of the pressure relief valve is indicated at 40, whilst reference 42 indicates the pressure transducer. The associated passage means includes a passage 44 leading to the pressure transducer, from which a branch passage 46 leads to the pressure relief valve 40. A passage 48 leads from the interior of the valve body to atmosphere. The valve member 50 within the body of the valve 40 normally seals the mouth of the branch passage 46 where it opens into the valve body, but is liftable, as described hereinafter, to open the branch passage 46 to the interior of the valve body, from which the passage 48 opens to atmosphere. Reference 52 indicates the top of a member for effecting manual movement of the valve member, and reference 54 indicates a solenoid controlling automatic lifting of the valve member 50.

Figures 3 and 4 show the pressure relief valve in detail. Figures 3A to 3E relate in particular to manual operation, and Figures 4A and 4B to automatic operation. Referring first to Figure 3A, the pressure relief valve is shown in its normal rest condition. Solid rubber valve member 50 is compressed by spring 56 against the mouth of the passage 46, where this passage opens into a chamber 58 housing the valve member. The passage 48 from chamber 58, leading to the atmosphere, is not visible. An abutment 60 for the spring 56 is provided on a somewhat flexible stalk 62, which at its upper end suppoπs a rockable ratchet element 64. which has on one side a pawl 66 shown in Figure 1 to be latched beneath a closed position latch, which is conveniently provided by the tip of the stem 72 of a solenoid drive means 74 incorporating a spring 76.

The ratchet element 64 includes another pawl 77 on the side opposite to the pawl 66, and the body of the pressure relief valve has an internal open position latch 78 on the side opposite to and above the latch 70 provided by the solenoid drive means.

Above the ratchet element 64 within the valve body is a finger operable member 80 for effecting manual operation of the valve, the top end 52 of the member 80 being accessible at the top of the housing of the sensing unit and being visible in Figure 2, as heretofore mentioned.

The first stage of manual operation to open the valve is shown in Figure 3B. The finger operable member 80 is depressed to push down the ratchet element 64, thereby releasing it from the closed condition latch 70, accompanied by overcompression of the rubber valve member 50 and flexure of the stalk 62. Finger operable member 80 is now released, allowing spring 56 to lift the stalk 62, thereby lifting valve member 50 with it. This opens the chamber 58 to atmosphere, whereby excess pressure in the culture bottle is relieved via the needle, puncturing device, and passage means 46, 48. Figure 3C shows the valve in the condition assumed towards the end of the opening movement, and Figure 3D shows the valve at the end of the opening movement, when the stalk 62 has straightened, causing the ratchet element 64 to rock to an oppositely tilted condition from that of Figure 3 A, whereby the pawl 77 engages the open position latch 78. Finger operable member 80 has risen to the maximum permitted extent, exposing a top section of this member which is conveniently marked to show that the pressure relief valve is open.

It will be apparent that relief of an excess underpressure in the container can be achieved in a similar manner.

Re-closure of the valve is accomplished, as shown in Figure 3E, by pushing down the elevated finger operable member 80, again flexing the stalk 62 as the spring 56 is compressed during depression of the stalk and valve member 50. Eventually, the ratchet element 64 tilts back to its original condition to engage the closed condition latch 70, by which time the rubber valve member 50 is again partially compressed to seal the mouth of the branch passage 46.

In consequence of the foregoing description, it will be appreciated that operation of the pressure relief valve is by a click open/click closed action of the finger operable member 80.

Automatic opening of the valve is initiated when the microprocessor in the housing of the sensing unit produces a trigger signal responsively to detection of an internal bottle pressure exceeding, or possibly falling below, a predetermined threshold. The trigger signal causes temporary energisation of the solenoid drive means 74, whereupon the stem 72 is temporarily withdrawn, retracting the tip 70 of the stem, i.e. the closed condition latch, laterally, as indicated in Figure 4A, for a time period sufficient to release the ratchet element 64. The pressure relief valve thereby opens in the manner already described with reference to Figures 3 A to 3D, while the solenoid is de-energised to allow the closed condition latch 70 to restore under the action of the spring 76 (Figure 4B). The automatic operation is in one direction only, that of opening the pressure relief valve. Re-closure of the valve is effected manually, as already described with reference to Figure 3E.

While the above-described pressure relief valve is inexpensive to manufacture and is readily incorporated in the housing of the sensing unit, the present invention is not limited thereto, and the invention encompasses other possible constructions of pressure relief valve when incorporated in a sensing unit for monitoring the contents of a fluid-containing container.

Moreover, the use of the sensing unit is not restricted to that of monitoring liquid culture bottles. The sensing unit, with pressure relief valve incorporated, may be applied to monitoring biological oxygen absorption in water.

Claims

1. A sensing unit for monitoring the contents of a sealed fluid-containing container, comprising a housing having means enabling its connection to the container, the housing including a passage means through which the housing interior in use communicates with the container interior, whereby the container interior liable to pressure variations is placed in sealed communication with the housing to enable the container contents to be monitored, wherein the housing of the sensing unit incorporates a pressure relief valve which includes a valve member located in a branch of said passage means communicating with atmosphere.

2. A sensing unit according to claim 1 , wherein the pressure relief valve is manually operable.

3. A sensing unit according to claim 1, wherein the pressure relief valve is operable by a powered drive means.

4. A sensing unit according to claim 3, wherein a measurement device in the housing is responsive to pressure variations within the container and in the event of a predetermined upper or lower pressure limit being exceeded produces a drive signal for the drive means.

5. A sensing unit according to claim 3 or 4, wherein the drive means is a solenoid.

6. A sensing unit according to any one of claims 1 to 5, wherein the valve member is located in an enlargement in the said branch of the passage means into which opens a narrower passageway, and the valve member acts to open and close the mouth of the passageway.

7. A sensing unit according to claim 6, wherein the valve member is a rubber element compressed against the mouth of the passageway in the closed condition and displaced away from the passageway in the open condition.

8. A sensing unit according to any one of claims 1 to 7, wherein the valve member incorporated in the pressure relief valve is operable by an operating means having two spaced latched positions, one in which the pressure relief valve is closed and one in which it is open.

9. A sensing unit according to claim 8, wherein the operating means comprises a spring loaded, axially displaceable stalk interposed between the valve member and a ratchet element releasably engageable with either one of two latches spaced apart in the axial direction.

10. A sensing unit according to claim 9, wherein the ratchet element is disengageable from a closed condition latch and axially displaceable under spring action to engage an open condition latch by means of a finger operable member displaceable in the axial direction on said ratchet element.

11. A sensing unit according to claim 9 or 10, in which the ratchet element is disengageable from a closed condition latch and axially displaceable under spring action to engage an open condition latch by means of a solenoid driven, spring loaded member acting laterally to release the ratchet element by withdrawal of said closed condition latch.

12. A sensing unit according to any one of claims 9 to 11 , in which the finger operable member is axially displaceable to drive the ratchet element against the spring action out of engagement with the open condition latch and into engagement with the closed condition latch.

13. A sensing unit according to any one of claims 9 to 12, wherein the ratchet element has two pawls one on each side of the element, and a guide along which the stalk and ratchet element are displaceable has the two latches on opposite sides of the path of movement of the ratchet element, said ratchet element being tiltable from side to side, accompanied by flexure of the stalk, to enable the pawls to engage the respective latches.

14. A sensing unit according to any one of claims 1 to 13, wherein the housing accommodates a pressure transducer communicating with the interior of the container in the closed condition of the pressure relief valve.

15. A sensing unit according to claim 14, wherein the housing is adapted to fit sealingly to a closure device on the top of the container, and thereby automatically place the container interior in communication with the pressure transducer when the pressure relief valve is closed.

16. A sensing unit according to claim 15, when applied to monitor pressure variations in the headspace of a partially filled culture bottle.